Since construction vehicles are in most cases operated under severe conditions, it is necessary to carry out pre-operation checking, that is, checks and inspection for the amount of fluid and liquid filled in every part after the start of engines at the commencement of operations. Further, since construction vehicles get out of order or are damaged frequently, it is essential to carry out incessant maintenance and repairs.
Further, in dump trucks, the total weight of earth and sand carried by each truck per day corresponds to the daily volume of work done, and therefore it is important to measure the total weight of earth and sand carried by each of them per day accurately.
Firstly, it the pre-operation checking, it has previously been made by the driver of each truck by observing an electronic display unit to check whether the quantities of brake fluid, engine oil, hydraulic fluid, transmission oil, retarder fluid, radiator liquid and battery liquid are normal or abnormal.
Such an electronic display meter serves to display only normality and abnormality and cannot record the result of pre-operation checking. Therefore, if it is desired to record them, it is necessary to resort to human work, which is troublesome. Further, to summarize the result of pre-operation checks thus recorded, it is necessary to carry out the work while checking the record, which operation is very troublesome.
Further, in the respect of maintenance and repairs, it is seldom that maintenance control data on individual construction vehicles are recorded scrupulously. In particular, since construction vehicles are expensive, they are in most cases not owned by individual users, but hired from rental companies therefore it has been difficult to carry out maintenance and repair suitable for individual construction vehicles.
Further, the measurement of the total weight of earth and sand carried by each truck per day has heretofore been made by detecting the pressures in suspension cylinders of each dump truck, computing by means of a microcomputer the weight of earth and sand loaded thereon on the basis of the detected pressures, and printing out by means of a printer the total weight of earth and sand transported by each truck per day on the basis of the computed weight of them.
On the other hand, since dump trucks for construction work weigh several tons and carry several ten tons of earth and sand, their engines consume great quantities of fuel, and also the fuel consumption varies largely with the driving techniques of individual drivers. It is therefore important to learn the amount of fuel consumed by the engine, that is, the fuel consumption per unit time. For this purpose, it has heretofore been made by finding amount of fuel consumption after the previous time when the fuel tank is filled with fuel fully from the amount of fuel supplied into the tank, thereby finding the fuel consumption per unit time.
To find the weight of earth and sand carried by each truck per day according to the aforementioned conventional method of measurement, it is necessary to sum up the computed weight of earth and sand loaded on each truck by human work and write the sum of the weight of the load carried in a management ledger, which is very troublesome. Further, the conventional method of finding the fuel consumption per unit time is also very worrisome.